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Ok so I am growing a couple autos in coco coir. I'm using PureBlend Grow Pro and I think my coir is becoming too acidic from these PureBlend veg nutes. I have CalMag (actually, CaliMagic or whatever, but essentially the same thing..) but I haven't used any of it yet.
I told my local hydro dude that i am growing in coco with PureBlend nutes, and he recommended using the CalMag. My question is, does CalMag buffer your substrate's pH, as well as (obviously) deliver Ca and Mag? Will it significantly buffer my coir's pH, or do i need to invest in some pH-up?
Is there any recommended ratio of PureBlend-to-CalMag?

Fuzzy Duck

Well-Known Member
Coco coir nutrients need to be adjusted to aprox PH 5.8 for feeding you may need to get a PH pen to test water/nutrients before feeding adjust with suitable PH up or down.

Ca/Mg nutrients are advised as coco coir can inhibit the up take of such nutrients.

Regular feeding with chemical/synthetic based nutrients like every day may cause a build up of nutrients in the coir which may lead to nutrient burn, lock outs & an acidic growing medium.

Nutrients are general acidic in nature btw.


Member of the Month: Sept 2013 - Nug of the Month: July 2014, April 2020
Keep your feeds low like 1.2 ec for a few feeds. 1 ml calimagic per gallon is all you would really need if using tap, if your using ro water 2 maybe 3 for a heavy feeder would be sufficient. You should have some ph-up, I also use silica as a ph-up .

Feed between 5.8 and 6 ph.
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